Office file cabinet locking systems are known in the art. For example, a 1997 U.S. Pat. No. 5,599,077, listing Law and Parker as inventors, issued for a “Cabinet Locking System” and purports to disclose a system for preventing more than one drawer of a multi-drawer office file cabinet from opening at the same time and, also, for locking all of the drawers from opening. The system includes a U-shaped guide way formed by the cabinet side panel in which a stack of channel shaped members, called block units, are vertically movable. Each block unit has an aperture in a front surface to receive a locking member. Mounted in front of the stack of block units is an elongated angle element called a locking element that is fastened to the upper most block unit but movable relative to the other lower block units. The locking element has a series of locking slot designed to register with the aperture of each block unit. The locking element also includes elongated slots to accommodate rollers connected to the upper and lower ends of each block unit. The lower roller of an upper block unit is paired with an upper roller of the adjoining lower block unit. Attached to the side of each cabinet drawer is a side rail that engages a pair of rollers when the drawer is opened. This causes the block units and the locking element above the roller that is engaged to move upward. The result is that roller pairs above the engaged roller pair are misaligned with drawer rails of drawers above the opened drawer so as to prevent the non-opened drawers from opening. The misalignment causes drawer rails to abut a roller rather then slide into the nip between rollers. The drawers below the opened drawer cannot open because there is no vertical space available in the guide way to move either the block units or the locking element. When all of the drawers are closed, a locking member may move horizontally and be received by a registered aperture of a block unit and a locking slot of the locking element to preventing vertical movement of both the block units and the locking element.
Another U.S. Pat. No. 5,829,859, issued in 1998 to Cram for a “Bi-Directional Drawer System” and purports to disclose an office file cabinet having one set of drawers that may open from the front of the cabinet and another set that may open from the rear of the cabinet. Like the earlier mentioned '077 patent, a system for allowing only one drawer at a time to open is presented. The system uses a vertical stack of locking bars movable in a channel shaped support. The locking bars are also channel shaped. Each locking bar has rollers called cam followers attached to the bars ends such that pairs of cam followers operate just as in the '077 patent. Each drawer includes a rail, called a cam, with an inclined surface at the cam's leading edge. The locking bars are displaced either by a locking mechanism located above the stacked locking bars, the locking mechanism using a key operated cam, or displacement may come from a cam of an opened drawer. When displacement occurs the cam follower pairs of closed drawers are misaligned with the corresponding drawer cams such that an attempted drawer opening results in the cam abutting a cam follower. A spring beneath the stack of locking bars returns the locking bars to their non-displaced positions when an opened drawer is closed.
The inventions discussed in connection with the described embodiments below address deficiencies of the prior art. The features and advantages of the present inventions will be explained in or become apparent from the following summary and description of the preferred embodiments considered together with the accompanying drawings.